Tame

Posted on May 12th, 2012

We have all heard how tame the animals of the Galapagos are: tourists can walk right up to a Booby or Iguana or Hawk, and they do not flee. More extreme is St. Mark’s Square in Italy, famous for its pigeons landing on the heads and shoulders and hands of tourists. Your nearest city park may have its own phenomena, with squirrels eating out of someone’s hand.

Vietnamese potbelly pig lounging on sofa, watching TV.

If you yearn to get closer to wildlife, it is a thrill to find animals that don’t flee when we approach, or that approach us. A thrill, and very surprising. How can this be, when wildlife is usually so much more wild?

I’ve asked tour guides, naturalists, photographers, park rangers, and armchair naturalists about this, but always seem to get unsatisfactory answers. The simple answers I get don’t account for why a squirrel or pigeon in a city park might approach us, while animals in the Galapagos neither approach nor flee, while most animals in the wild flee when approached too closely. In this little post, I will sort through things, as best I can.

Fear

Fear is the force that sends us away from a spider or snake, and fear is the force that sends most wild animals away from us. The squirrels in the city park, like the animals of the Galapagos, must somehow lack fear of humans.

“Fear” is an emotional state, triggered by a perceived threat. Fear energizes us for action by accelerating the heart, dilating blood vessels for muscles, constricting blood vessels to many parts of the body, increasing muscle tension, and increasing our respiration rate. With this new physiological state, it becomes easier to take action to deal with the perceived threat. The many physiological symptoms that humans experience when they feel fearful can be measured in other animals, too, and there can be no dispute that all species experience the same basic physiological state when threatened. If we label our state as “fear”, we should be comfortable using the same label for squirrels, cockroaches, and snails.

The response to fear varies with the threat, the species, the individual, the situation. Flight or fight may occur. But some situations may produce freezing, as when an opossum “plays possum” or a fawn holds perfectly still as danger approaches.

Fears develop in different ways.

The Startle Response. Many people seem to believe in “instinctive fears”. It seems reasonable that some fears would be innate – not require learning. Consider our friend the hermit crab. Hermit crabs don’t seem to see anything beyond a foot or so, so use forceps to offer one some dinner, and the inevitable first reaction is to jump back – the “startle response.” After a few seconds, Mr. Crab realizes that this is dinner, not danger, and grabs his snack to begin eating. All hermit crabs seem do this, no matter how many times they’ve been hand fed. It seems safe to say that there are some cases of “instinctive fear”.

Pre-Natal Terror. One study suggests that fear can be learned in the womb – at least for crickets. In one studyi, gravid crickets were caged with a predatory wolf spider whose fangs had been capped with wax, to allow Mrs. Cricket to live long enough to do something. The wolf spider was then taken away, Mrs. Cricket laid her eggs and went off, and eventually the eggs hatched. The offspring were much more cautious around a wolf spider than those in a control group who had no exposure in the womb. On average, those exposed spent 27% more time keeping completely still – a good cricket defense – in the presence of the spider. They also spent twice as much time hiding from the spider, in comparison to the control group, and survived longer as a result. Other studies cited by Storm and Lima (2010) show that maternal exposure to predators can alter the phenotype of offspring, improving their defenses to the predator. In the absence of such predators, the phenotype is “normal”.

Fears of our Forefathers. Cook & Mineka (1989) experimented with lab-raised rhesus monkeys who were not afraid of toy snakes, toy crocodiles, flowers, or toy rabbits. The monkeys were shown videos of model monkeys behaving fearfully toward these four objects (they had to dub in the flower and rabbit images, because their actors were not actually afraid of them.) The monkey observers of these films acquired a fear of the toy snakes and toy crocodiles, but not the flowers or rabbit. The study suggests that observing fear in others leads to fear acquisition only when the stimuli are fear-relevant.ii Humans might be fear-relevant to deer, in which case a fearless fawn might quickly learn fear of humans when first seeing an adult run away. But humans are not fear-relevant to dogs, and puppies will not learn to fear humans so easily. Öhman & Mineka (2003) write “Intense snake fear is prevalent in both humans and other primates. Humans and monkeys learn snake fear more easily than fear of most other stimuli…”iii The same quick learning of fear of spiders seems to happen, too.

Heightened sensitivity. Our fears of snakes and spiders are not exactly instinctive, but something’s going on here. Research with infants and toddlers and finds that we aren’t born afraid of spiders and snakes, but even three-year olds can detect a snake or spider in a picture more quickly than they can spot a frog or caterpillar or flower in the pictures. And studies find that even a 7 month old can learn a fear of spiders and snakes faster than they learn other fears. Fears may develop in infants, during a sensitive period. But infants can also learn to not fear spiders. For some communities such as Papua New Guinea and parts of South America, spiders are included in traditional foods.iv

Habituation

Habituation overrides fear. When an animal becomes habituated, it is less likely to run away.

Repeated presentation of a stimulus will cause a decrease in reaction to the stimulus. Fear is often reduced by repeated exposure to the object of the fear, particularly if each exposure is as pleasant as possible. Treating arachnophobia involves various approaches that repeatedly present spiders or spider images to the patient. As HelpGuide.org says, “The most effective way to overcome a phobia is by gradually and repeatedly exposing yourself to what you fear in a safe and controlled way. During this exposure process, you’ll learn to ride out the anxiety and fear until it inevitably passes. With each exposure, you’ll feel more confident and in control. The phobia begins to lose its power.”v

Curiosity

Curiosity is a powerful force in all creatures with any mobility – from insects through fish to apes. The need to explore, inquire, investigate, and learn underlies finding food, finding safe places. Curiosity can draw a wild animal closer to us. We’ve all had experiences where an animal approached us – perhaps only briefly – until it figured out what we were.

Observational Learning

When a squirrel in my yard sees another squirrel taking a nut from my front porch, it learns about the nuts. It sees that some other squirrel was able to get a nut without getting mauled. Observational learning is probably important in a fawn’s development of fear of humans – mom runs away, so I’d better too. And it is important in a squirrel’s decision to investigate my front porch. In the Galapagos, where parents do not flee humans, their young learn to not flee. Observational learning can motivate approach or avoidance of humans.

Classical Conditioning

I have managed to confuse my horse. When I walk him to the barn, I give him a steady supply of sliced carrots. When we head back to the pasture, he gets what I have left. I have deliberately made his walks with me as pleasant as possible. So perhaps it is no wonder that when he sees me, he comes across the pasture to the gate. (But some wonder. I know many horses that move away from their owners in this situation. Some horses are uncatchable.) And no wonder that he is sometimes licking his lips as he walks toward me. I’ve tried to “pair” myself with food. He loves to eat, he has come to love me.

Another rider once said to me “You cheat. You use carrots.” Others say that I “spoil him.” I don’t think that making your horse happy is cheating or spoiling him. Don’t we want our horse to be happy? Aren’t we happy when our horse is happy?

We want wildlife happy. Like horses, for most wildlife food is the way to their hearts.

Filial Imprinting

Imprinting goes beyond habituation. A chick decides what kind of bird it will be by paying attention to those around it when it is very young. If those others are other birds of the same species, the chick will behave more like those others it has observed, and flock with them. If those others are humans, a chick may come to act as if it is human, and will want to be with humans. In birds, imprinting is a powerful force in tameness, but it is also very destructive. A bird that has imprinted on a human makes a terrific pet, but a terrible bird. Imprinted birds cannot be released back into the wild.

Genetics

For some species – maybe for many species – it is possible to breed for friendliness. Our best known experiment is how early humans selected wolves for friendliness, and in just 15,000 years were able to develop the dog. But early humans were probably just kinder to those wolves that were kind to them – or that barked to warn them of approaching trouble at night. Far more remarkable is the result of what can happen when we seriously breed for friendliness. In just a few years of careful selection, Dmitry Belyaev was able to produce silver foxes that were as friendly as any dog. The researchers were able to achieve the same results with two other species they experimented with: mink and rats.

Selecting for friendliness seems to alter their physical appearance. “Selecting which foxes to breed based solely on how well they got along with humans seemed to alter their physical appearance along with their dispositions. After only nine generations, the researchers recorded fox kits born with floppier ears. Piebald patterns appeared on their coats. By this time the foxes were already whining and wagging their tails in response to a human presence, behaviors never seen in wild foxes.”vi

Putting it Together

So fear can drive a wild animal away from us. Habituation can overcome fear. Curiosity, observational learning, classical conditioning, and imprinting can pull an animal closer.

Approach/Avoidance conflicts occur when an animal is motivated to approach and simultaneously motivated to avoid. A squirrel in my front yard knows that a tree is a safer place to be, but being at my feet is more likely to result in a nut. If I sit quietly without making eye contact, I do not add to his need to avoid. If he sees several nuts at my feet, his desire to approach is increased. Mr. Squirrel demonstrates the conflict by approaching me in a circuitous route, tail twitching, feet spread ready to take off. The closer he gets, the more excited he gets: more troubled, more eager. Habituation reduces his fearfulness, and the reward that comes from finally reaching the nut will increase his desire to approach. Eventually, the conflict goes away. Now Mr. Squirrel is sitting on the sofa, watching TV.

We have an expectation that animals will fear us, and flee when we approach. This is one reason why a visit to the Galapagos is so wonderful, and one reason why we may become anxious or frightened when an animal does not flee as we approach.

So why aren’t the birds, mammals, or reptiles of the Galapagos afraid of us? It is possible that as young, they have never seen an adult fearful of us.

Why would this cockatiel, a wild bird from Australia, be sound asleep on my leg? Because its line was bred for friendliness since being taken from the wild. And because it is imprinted.

And why would squirrels in a city park approach you for a peanut, but squirrels in the woods scamper away? Those in the woods have likely seen an adult squirrel scamper away on our approach. Those in the city may or may not have seen this, but their fear has been reduced by habituation, and through classical conditioning they have learned that they may be fed if they approach. Both city and country squirrels have adapted nicely, but in opposite ways.

“Tameness” involves lots of processes. There are lots of short answers to why an animal is tame… but usually none of them will be right.

v Phobias and Fears. Symptoms, Treatment, and Self-Help. http://www.helpguide.org/mental/phobia_symptoms_types_treatment.htm But flooding with a feared stimulus appears to produce long-lasting changes in behavior for only some of us. Mineka, Keir, and Price (1980) gave wild-reared rhesus monkeys, all initially fearful of both real and toy snakes, repeated exposure to them. Using various measures, the researchers concluded that substantial long-lasting changes occurred in only 3 of 8 monkeys tested.